This invention relates to a test rack for electronic equipment which is adapted such that the rack table on which the equipment is placed can be inclined through a simple and smooth operation.
Test racks of the type described are well known in the art, a typical example of which is shown in FIG. 1. Specifically, FIG. 1A shows the construction of a table inclination apparatus which is mounted on the bottom of the rack, FIG. 1B a front view of a stopper plate, and FIG. 1C a cross-sectional view showing a pin inserted into the stopper plate. The stopper plates 10, 10' are secured to test rack leg supports 12, 12', respectively, and have a plurality of holes 13 bored therethrough along one edge thereof, as illustrated in FIG. 1B. The pin 14, 14' are pivotally mounted at one end to each of cams 17, 17' so as to lie at right angles to the lever shaft 16 of a lever 15, and is adapted such that the other end thereof penetrates a hole 13 in the stopper plates 10, 10' by passing through a bearing hole 19 provided in the side of the table 18. In accordance with this conventional arrangement, pulling the lever 15 forward rocks the cams 17, 17' and causes the pin 14, 14' to move inwardly toward the center of the table 18 so that the tip of the pin is extracted from the hole 13 in the stopper plates 10, 10' thereby allowing the table to be tilted at a desired angle where it is then secured by releasing the lever 15, the latter being pulled back to its original attitude by a spring 20 so that the pin 14, 14' again slides into the prescribed hole 13 to lock the table 18 in place.
The disadvantage encountered in the conventional apparatus as described above is biting or scoring phenomenon that occurs between the pin 14, 14' and the hole 13 or between the pin and the hole 19 whenever a heavy load is placed upon the table 18, this phenomenon making it difficult to extract the pin 14, 14' from the holes. The result is that considerable force must be applied to the lever 15 to extract the pins before the table can be changed to another angle of inclination. One reason for the above problem is the perpendicular relationship between the pin 14, 14' and the direction in which the table 18 tilts. Specifically, the hole 13 and the hole 19 must be in perfect alignment owing to the perpendicular attitude of the pin 14, 14' with respect to the side of the table, but this alignment cannot be maintained when the heavy load is set upon the table. This misalignment of the holes causes the stopper plates 10, 10' and the side of the table to bite into the pin. Another reason is that sufficient play must be provided between the pin 14 and the bearing hole 19 since the pin is connected to the lever shaft 16 through the cam 17 and therefore undergoes arcuate motion as the cam rotates. This arrangement also invites the biting or scoring problem described above.